Bladder ’pacemaker’ could soon be a reality

In the near future, patients suffering from urinary incontinence may receive a new type of implanted electrode to provide relief when conventional treatment fails. One reason for urinary incontinence is a disturbance of the autonomic nervous control of the bladder which can cause it to become over-active. The new electrode will, through electrical nerve stimulation, suppress the activity and thus relieve the symptoms of urinary incontinence. The potential is enormous, but one of the challenges is developing the electrode so that the body will accept it. This issue is being addressed by Professor Hans Nørgaard Hansen of DTU Mechanical Engineering.  

 

In Denmark alone approximately 400,000 people suffer from urinary incontinence, and in Europe the number is estimated to be around 40 million. Urinary incontinence can be a huge social problem for sufferers, and the problem is also significant from a socioeconomic perspective. Though not all patients will be eligible for the implantable device, the invention still brings hope of increased quality of life for many people, while the commercial prospects of the project are also very promising.     

The idea is to develop an improved type of bladder pacemaker suitable for long-term implantation. In order for this to succeed, many different aspects must unite to work together. For instance, the electricity must be directed so that it targets very specific nerve branches. It must also be ascertained that the electrode is securely anchored in the body tissue to prevent it moving away from the nerve over time. 

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Figure 1: An overview of the implanted parts of the system, consisting of an electrode connected to an implanted pulse generator. The system can be implanted under local anaesthesia with special surgical instruments. It is a kind of pacemaker for the treatment of pelvic floor problems. The implant is remote controlled by the user with an external stimulator (not shown).

 

The art of fooling the body

The challenge of getting the body to accept the electrode contains elements of physiology, anatomy and hard core physics. It’s possible to fool the body into incorporating the electrode if it is covered with a surface that makes it easy for the body’s cells to take hold.   

Neurodan A/S, a partner company involved in the project, has already developed an electrode that can correct the problem of ”foot drop” – the difficulty or lack of ability to lift the front part of the foot. The electrode activates specific muscles in the leg every time the foot is lifted from the ground. But the foot is one thing, and the tissue around the bladder is quite another.    

DTU Mechanical Engineering’s project focus is to develop production methods that will make it possible to manufacture the tiny electrodes with microstructured surfaces. In addition to the involvement of DTU Mechanical Engineering and Neurodan A/S, the project also includes the Danish Technological Institute and Aalborg University.

 

The smaller the electrode, the harder it is to work with / Small and intricate 

But creating the right surface structure for the electrode is easier said than done, because making the outer shell of the electrode requires the use of an injection moulding process. And this is a major obstacle to overcome: the electrode is very small and features a complex 3D geometry whose purpose is to ensure that the electrode does not turn and move in the body. In order to establish microstructures on the surface of the electrode, new technologies must be developed to create the special injection moulding tool. And finally, the electrode itself must be made from biocompatible materials, which are very difficult to work with.  

 

Huge potential

If Professor Hans Nørgaard Hansen succeeds in finding the right surface and transferring it to a small and three-dimensional element, there will be many potential uses other than the electrode for the treatment of urinary incontinence. This is because the art of mastering the production of microgeometry offers possibilities far beyond the area of medical technology, for instance in connection with the development of self-cleaning surfaces.   

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Figure 2: One of the experimental electrodes tested for permanent stimulation of the pelvic floor nerves. The electrode is approx. 15 mm long and 1.2 mm thick. 

 

Facts:

The project is entitled: ”Advanced surface treatment for implantable medical devices”. The project duration is 4 years until the end of 2015, and the project has a total budget of DKK 27.6 million, of which DKK 13.8 million is provided by The Danish National Advanced Technology Foundation.

The project is carried out in conjunction with: Neurodan A/S, Aalborg University, Center for Sensory-Motor Interaction, The Danish Technological Institute, Radboud University Nijmegen Medical Centre in the Netherlands and Hoowaki in the USA.